Experimental Study of Self-Healing Characteristics and Insulation Resistance of Metallized Polypropylene Film under Various Inter-Layer Pressure

The self-healing of metallized film capacitor’s performance after dielectric breakdown is a unique ability making them high reliable, attractive for application under high voltage stresses, including pulse voltages typical for power electronics applications. The actual metallized film capacitors are tightly wounded rolls with inter-layer pressure declining from peak values counting tens of bars around the mandrel to units of bars in top layers. This work presents experimental findings of self-healing process characteristics such as energy, duration and micro-arc discharge time-dependent resistance under actual inter-layer pressures typical for metal-film capacitors. The insulation resistance of stacked metallized polypropylene films after self-healing under high pressures were found to be decreasing, resulting in current leakages to occur. Current leakages origination was associated with feasible carbon deposition near the breakdown channel due to polymer decomposition in high temperature arc discharge. Obtained results show the proper choice of film winding tension importance for capacitor’s reliability.